Study Of Laser Precision Ablating Functional Structure Patterns On Large-scale Complex Surface

Parts with complex surfaces have become the most commonly used cores components in aerospace,energy and power,automotive electronics and other fields.With the rapid development of modern industry,it is often necessary to manufacture functional structures with high precision and high efficiency on the surface of these parts in order to obtain some special surface properties such as microwave emission,wear and corrosion resistance,and hydrophilic and hydrophobic,etc.It is a great challenge for the modern manufacturing industry to fabricate functional structures with high efficiency,high precision and low cost.The main reason is that the size difference between the functional structure to be processed and the complex surface parts is even 10~6 times which is a typical cross-scale manufacturing.And the material of the parts is always difficult to be processed.Over the years,the mechanical milling,chemical mask etching and other methods are used to fabricate the functional structure and these methods have made some progress.However,the forming accuracy,efficiency and quality cannot meet the demand of practical engineering.In this paper,a creative method of Laser Projective Ablation Galvanometer Scanning(LPAGS)for fabrication of functional structures on complex surfaces.is presented.The research work around the processing equipment principle,basic theory of LPAGS,the technological flows,the error source analysis and compensation,the quality control and optimization,and industrial application have been carried out.The main results are as following:The theoretical system of LPAGS processing technology have been established and improved.The processing principles of LPAGS are based on three understandings:First,based on the principle of parallel projection transformation,the functional patterns on the surface can be transformed into two-dimensional projection processing patterns;Second,according the reversibility of the light path,the process of curved surface can be completed by focused laser beam which follows the scanning trajectory generated by the projection processing patterns;Third,laser spot size and energy distribution remain constant in the range of focusing lens depth of focus(DOF).It means that the effects of laser ablation are essentially the same as long as the topographical unevenness on the part surface is located inside"depth of focus".The technological flows contains:1)three-dimensional modeling of complex surface of components;2)surface modeling of functional structures;3)division of complex surface;4)generation of scanning trajectory;5)surface projection processing.The reasonable and precision functional structures can be established on surface by equal arc length projection.Using LPAGS method,the complex surface should be divided into a series of sub-areas,sub-blocks and sub-layers.The criteria of division in LPAGS are also established.For the criterion of division into sub-areas,the variation range of laser incident angle should be less than the maximum allowable change angle.The criterion of dividing block is decided by the machining accuracy and the scanning area of galvanometer while the slicing criterion of surface is determined by the laser parameters and the optical focus system.The division of sub-areas is based on the algorithm of K-means clustering and binary space partitioning,and the Cohen-Sutherland cutting algorithm is used to complete the division of sub-blocks and sub-layers.Based on the theory of multi-body system,the geometric error model of"5+3"LPAGS equipment is established,and on the basis of geometric error model a sensitivity analysis model is used to identify the key geometric error sources parameters of LPAGS equipment.According to the result of analysis,the way of real-time detection is adopted to adjust the assembly precision of the LPAGS equipment.The bilinear interpolation correction algorithm is used to correct the galvanometer scan distortion.After correction,when the processing field is 40×40 mm,the dimensional accuracy can reach±10?m.The Taguchi method is used to explore the influence of processing parameters on the LPAGS processing results.The laser power and laser incident angle are two important parameters affecting the LPAGS machining results.The method of LPAGS is verified on the“5+3”axis LPAGS equipment,and the method is successfully applied to the actual industrial production,such as completing the precision fabrication of frequency selection surface(FSS)of radar cover and phone antenna.